TWI672487B - Gas detection wafer and manufacturing method thereof - Google Patents

Abstract

The invention provides a gas detection wafer and a manufacturing method thereof. The gas detection wafer includes a substrate, an electrode unit provided on a part of the surface of the substrate, and a sensing layer formed on the exposed surface of the substrate and the electrode unit. The material of the electrode unit includes graphene and a conductive polymer. The sensing layer is made of zinc oxide. The method for manufacturing the gas detection wafer includes step (a): covering a surface of a substrate with a graphene layer, and patterning the graphene layer using a short pulse laser to form two electrodes spaced apart from each other. Electrode unit and step (b): growing zinc oxide by hydrothermal method on the exposed surface of the electrode unit and the substrate to obtain a sensing layer composed of zinc oxide, and the temperature of the hydrothermal method is not more than 90 ℃.

Description

Gas detection wafer and manufacturing method thereof

The invention relates to a detection wafer, in particular to a gas detection wafer.

Gas sensors are commonly used for the detection of alcohol, harmful gases, or flammable gases. They can be used indoors, in factories, or to detect human bodies for environmental or health purposes. At present, air pollution in Taiwan is extremely serious, which has seriously affected people's quality of life. Long-term inhalation of air containing pollution sources will cause lung disease. In addition, some studies have pointed out that when the human body is infected with diseases, the composition of exhaled gases will change. The detection of surrounding or self-exhaled gases will avoid the dangers of air pollution and allow instant health monitoring. Therefore, the development of portable and lightweight gas sensors that are thin and easy to detect has become the trend of gas sensor technology development. .

At present, most general gas sensors use the lithography process with vapor deposition to produce metal electrodes and sensing layers on the substrate. Therefore, the substrate used must be able to withstand high temperatures and must be performed in a vacuum environment. The process conditions are relatively high. In addition, the manufactured gas sensor needs to be heated or irradiated with UV light to improve the sensitivity when sensing, and the detection method is more complicated, so it cannot be used as a portable gas sensor that can detect gas instantly and easily.器用。 Use.

Therefore, an object of the present invention is to provide a gas detection chip that can be sensed at normal temperature.

Therefore, the gas detection wafer of the present invention includes a substrate, an electrode unit, and a sensing layer.

The electrode unit is disposed on a part of the surface of the substrate and includes two electrodes spaced apart from each other. The materials of the electrodes include graphene and a conductive polymer.

The sensing layer is made of zinc oxide as a material and is formed on the exposed surface of the electrode unit and the substrate.

In addition, another object of the present invention is to provide a method for manufacturing the gas detection wafer.

Therefore, the method for manufacturing the gas detection wafer of the present invention includes step (a): covering a surface of a substrate with a graphene layer, and patterning the graphene layer by using a short-pulse laser to form one having two Electrode units of spaced electrodes, and step (b): growing zinc oxide by hydrothermal method on the exposed surface of the electrode unit and the substrate to obtain a sensing layer composed of zinc oxide, and the hydrothermal method The temperature is not more than 90 ° C.

The effect of the present invention lies in that the material of the electrode unit is selected from the group consisting of graphene with good conductivity, and the zinc oxide nanowire made by the low-temperature hydrothermal method is used as the material of the sensing layer, so that the gas detection wafer of the present invention is manufactured. It is relatively simple. In addition, the manufactured gas sensor can be sensed at normal temperature without light or heating, so that the gas detection chip can be applied to a portable gas sensor.

Referring to FIG. 1, an embodiment of a gas detection wafer according to the present invention includes a substrate 2, an electrode unit 3, and a sensing layer 4.

The substrate 2 is used for supporting purposes, and may be selected from insulating polyethylene (PE), polyethylene terephthalate (PET), or polydimethylsiloxane (PDMS) ) And other materials.

In some embodiments, the substrate 2 may be selected from the above polymer materials and has flexibility.

The electrode unit 3 is disposed on a part of the surface of the substrate 2 and includes two electrodes 31 spaced apart from each other for outputting a sensing current. It should be noted that the materials of the electrodes 31 include graphene and a conductive polymer, and the shapes of the electrodes 31 may be interdigitated electrodes that are respectively inserted to increase the area of current conduction during sensing.

The sensing layer 4 is made of zinc oxide as a material, and is formed on the bare surface of the substrate 2 and the electrode unit 3 to adsorb gas molecules to be measured.

When using this embodiment to detect a gas, a current is passed through the electrode unit 3 and the sensing layer 4, and a gas to be sensed is passed through the sensing layer 4, and the adsorption of the sensing layer 4 is measured by measuring The detection result can be obtained by the change in resistance before and after the gas molecules.

The gas detection wafer of the present invention uses graphene as a constituent material of the electrode unit 3, and has better conductivity, so that when the sensing layer 4 grown on the electrode unit 3 senses a gas, the sensing current is easier to borrow. It is derived from this electrode unit 3. In addition, the substrate 2 can be further made flexible, so that the gas detection chip can be applied to a portable gas sensor.

The manufacturing method of the foregoing embodiment is described below:

The manufacturing method of this embodiment includes steps 91 and 92.

As shown in FIG. 2A to FIG. 2C, in step 91, a surface of the substrate 2 is covered with a graphene layer 5, and the graphene layer 5 is patterned by using a short-pulse laser to form the graphene layer 5. The electrode unit 3 has two electrodes 31 spaced apart from each other.

In detail, the graphene layer 5 is obtained by spin-coating a graphene ink 51 on the surface of the substrate 2 and then drying and curing the graphene ink 51. It should be noted that the graphene ink 51 may be obtained by dispersing graphene in a conductive polymer solution, and then spin coating the surface of the substrate 2 and baking at 130 ° C to 150 ° C for 2 hours to dry and form a film. Graphene is dispersed in a reactive monomer, spin-coated on the surface of the substrate 2, and then baked and hardened at the curing temperature of the reactive monomer. The conductive polymers are selected from the group consisting of poly (3,4-ethylenedioxythiophene) (PEDOT), poly (p-phenylene sulfide (PSS)), Or polyaniline (Polyaniline, PANi), the reactive monomers are selected from 3,4-ethylenedioxythiophene, p-phenylene sulfide, or aniline. the graphene ink 51 may further comprise a diluent to adjust the viscosity of the ink graphene 51 of the short pulse laser may be a femtosecond laser or a picosecond laser pulse time of 10 ^-12 to 10 ^{- 15} seconds with a wavelength of 532 nanometers. The extremely short pulse time can reduce the heat-affected zone, thereby reducing the extent to which the graphene layer 5 is heated to change its properties, and the edges of the electrodes 31 formed are flatter, which can reduce the sensitivity. Noise during the test.

With reference to FIG. 2D and FIG. 2E, the step 92 is to grow zinc oxide by hydrothermal method on the exposed surfaces of the electrode unit 3 and the substrate 2 to obtain the sensing layer 4 composed of zinc oxide, and the hydrothermal method The temperature is not more than 90 ° C.

Specifically, in step 92, a seed solution 6 is drip-coated before the surface of the substrate 2 on which the electrode unit 3 is formed, and the exposed surface of the substrate 2 and A zinc oxide seed film 41 is formed on the surface of the electrode unit 3 (as shown in FIG. 2D), and then the substrate 2 on which the zinc oxide seed film 41 is formed is immersed in a growth solution 7, and a low-temperature hydrothermal method is used. Under the temperature condition of 80 ° C. to 90 ° C., a plurality of zinc oxide nanowires 42 are grown from the zinc oxide seed film 41 to form the sensing layer 4.

It should be noted that the seed solution 6 includes zinc acetate dehydrate, triethylamine, and isopropyl alcohol, and the zinc acetate two in the seed solution 6 The molar ratio of the water compound to the triethylamine is 1: 1.

It should be further explained that the growth solution 7 contains cyclohexamethylenetetramine, Zinc nitrate Hexahydrate, and water. The volume concentration ratio of the cyclohexamethylenetetramine to the zinc nitrate hexahydrate is 1: 1, and the volume concentration of the zinc nitrate hexahydrate is at least 0.01M, which can reduce the growth time of the zinc oxide nanowire. .

The manufacturing method of the gas detection wafer of the present invention uses short pulse laser for patterning to form the electrode unit 3, and is matched with a low-temperature hydrothermal method. Compared with the conventional gas detection wafer manufacturing method, the lithography process is used with vapor deposition. Method, the method for manufacturing the gas detection wafer of the present invention is not only relatively simple and easy to manufacture, but also has a low overall manufacturing temperature, so a flexible polymer material can be used as the material of the substrate 2 to make the gas produced. The detection chip is flexible and can be applied to, for example, a portable or wearable gas sensor.

In order to explain the gas detection wafer and the manufacturing method of the present invention more clearly, the manufacturing method of the gas detection wafer and the related characteristics of the gas detection wafer are described in detail below with specific examples.

The detailed production steps of this specific example are as follows:

A graphene ink 51 (type: I-MS18) was spin-coated on the surface of the substrate 2 made of polyethylene terephthalate, and then baked at 150 ° C. for 2 hours to dry and form a film to form the graphene layer 5. The graphene layer 5 was then patterned into a pair of interdigitated electrodes using a short pulse laser (repetition rate of 300 kHz, energy flux of 1.35 J / cm ² , and laser speed of 500 mm / s). 31 electrode units 3, and the two interdigitated electrodes 31 face each other and are interposed.

Preparation of the seed solution 6: After dissolving 1.1 g of zinc acetate dihydrate in 50 ml of isopropanol, heat to 85 ° C. and stir for 15 minutes, and then add 700 μl of triethylamine with a concentration of 5 mmol. The isopropyl alcohol solution was stirred at 85 ° C. for 10 minutes, and then cooled to room temperature and left for 3 hours to complete the preparation of the seed solution 6.

Configure the growth solution 7: add 5.61 g of cyclohexamethylenetetramine to 800 ml of deionized water, then add 11.9 g of zinc nitrate hexahydrate to the deionized water, and stir at room temperature for 24 hours to complete the Preparation of growth solution 7.

The seed solution 6 is drip-coated on the bare surface of the substrate 2 on which the electrode unit 3 is formed and the surface of the electrode unit 3, dried at room temperature to form the zinc oxide seed film 41, and then rinsed with ethanol. Substrate 2, then baked at 100 ° C. for 20 minutes to cure the zinc oxide seed film 41, and then immersed the substrate 2 in the growth solution 7 at 85 ° C. for 8 hours, and then on the zinc oxide seed film 41 By growing the zinc oxide nanowires 42 (as shown in FIG. 3) to form the sensing layer 4, the production of the specific example is completed.

It should be noted that, in the manufacturing steps of the above specific example, the seed solution 6 and the growth solution 7 may be prepared before the electrode unit 3 is prepared, and the seed solution 6 and the growth solution 7 may be prepared. The order is not limited, and the growth solution 7 can be prepared first and then the seed solution 6 can be prepared.

Referring to FIG. 4 and FIG. 5, FIG. 4 is a result of sensing nitric oxide at 25 ° C. in the specific example, in which the concentration of nitric oxide passed in is 150 ppm and 300 ppm, and FIG. 5 is the use of the specific example at 25 ° C. As a result of five cycles of sensing, the gas circulating through is nitric oxide and nitrogen, and the thick line represents the nitric oxide concentration being 300 ppm, and the thin line represents the nitric oxide concentration being 150 ppm. It can be known from the sensing results of FIGS. 4 and 5 that the gas detection chip can indeed sense gas at room temperature, and the sensing sensitivity is high. In addition, the difference in sensing results obtained by each cycle is not large, indicating that the gas The detection wafer has high accuracy and can maintain the efficacy of the detection gas even after repeated sensing.

In summary, the gas detection wafer of the present invention has flexibility through the substrate 2, and the material of the electrode unit 3 includes graphene, and the sensing layer 4 is made with a low-temperature hydrothermal method to make the gas detection wafer The manufacturing process is simple and can be performed at low temperature. In addition, the gas detection chip can perform gas sensing at normal temperature without additional light or heating. The detection method is simple and can be applied to flexible or wearable gas sensing. Device, it can indeed achieve the purpose of the invention.

However, the above are only examples of the present invention. When the scope of implementation of the present invention cannot be limited in this way, any simple equivalent changes and modifications made in accordance with the scope of the patent application and the content of the patent specification of the present invention are still Within the scope of the invention patent.

2‧‧‧ substrate

3‧‧‧ electrode unit

31‧‧‧electrode

5‧‧‧ graphene layer

51‧‧‧graphene ink

6‧‧‧ seed solution

4‧‧‧sensing layer

41‧‧‧zinc oxide seed film

42‧‧‧zinc oxide nanowire

7‧‧‧ Growth Solution

91, 92‧‧‧ steps

Other features and effects of the present invention will be clearly presented in the embodiment with reference to the drawings, in which: FIG. 1 is a schematic diagram illustrating an embodiment of the gas detection wafer of the present invention; FIGS. 2A to 2E are schematic flowcharts, Describe the method for manufacturing the gas detection wafer of the present invention; FIG. 3 is an electron microscope photograph illustrating the structure of a sensing layer in a specific example of the gas detection wafer of the present invention; FIG. 4 is a time-to-resistance diagram illustrating the specific Example is the result of sensing nitric oxide; and FIG. 5 is a time-response relationship diagram illustrating the result of cycling sensing of different concentrations of nitric oxide in this embodiment.

Claims (10)

A gas detection chip includes: a substrate; an electrode unit provided on a part of the surface of the substrate, including two electrodes spaced apart from each other, and the materials of the electrodes include graphene and conductive polymers; and a sensing layer It is made of zinc oxide and is formed on the exposed surface of the electrode unit and the substrate. The gas detection wafer according to claim 1, wherein the substrate has flexibility. The gas detection wafer according to claim 1, wherein the material of the substrate is selected from polyethylene, polyethylene terephthalate, or polydimethylsiloxane. The gas detection wafer according to claim 1, wherein the electrodes are finger electrodes corresponding to shapes. A method for manufacturing a gas detection chip, comprising: step (a): covering a surface of an insulating substrate with a graphene layer, the graphene layer comprises graphene and conductive polymer, and the graphene is applied by short pulse laser The layer is patterned to form an electrode unit having two electrodes spaced apart from each other; and step (b): growing zinc oxide on the exposed surface of the electrode unit and the substrate by hydrothermal method to obtain a zinc oxide Constitute the sensing layer, and the temperature of the hydrothermal method is not greater than 90 ℃. The method for manufacturing a gas detection wafer according to claim 5, wherein the graphene layer is formed by spin coating graphene ink containing graphene and a conductive polymer or conductive reactive monomer on the surface of the substrate form. The method for manufacturing a gas detection wafer according to claim 5, wherein the pulse time of the short pulse laser is 10 ^-12 to 10 ^-15 seconds. The method for manufacturing a gas detection wafer according to claim 5, wherein the step (b) is to form a zinc oxide seed film before the exposed surface of the substrate and the surface of the electrode unit, and then use the hydrothermal method to A large number of zinc oxide nanowires are grown on the zinc oxide seed film to form the sensing layer. The zinc oxide seed film is formed at a temperature of 20 ° C. to 30 ° C., and the zinc oxide nano wires The growth temperature is 80 ° C to 90 ° C. The method for manufacturing a gas detection wafer according to claim 8, wherein the zinc oxide seed film is formed by dropping a seed solution containing zinc acetate dihydrate, triethylamine, and isopropanol on the electrode The unit is prepared after the substrate, and the molar ratio of the zinc acetate dihydrate and triethylamine is 1: 1. The method for manufacturing a gas detection wafer according to claim 8, wherein the zinc oxide nanowires are immersed in the substrate on which the zinc oxide seed film is formed, containing a cyclohexamethylenetetramine and After the aqueous solution of zinc nitrate hexahydrate is grown on the zinc oxide seed film, the volume concentration ratio of the cyclohexamethylenetetramine and the zinc nitrate hexahydrate is 1: 1, and the zinc nitrate The volume concentration of hexahydrate is at least 0.01M.